Marijuana, expectancies, and post-traumatic stress symptoms: a preliminary investigation

Previous work suggests that people might turn to marijuana to alleviate the symptoms of post-traumatic stress disorder (PTSD) and associated distress. Expectancy theories emphasize that the use of drugs correlates with their anticipated effects. The current study examined multivariate links among marijuana use, PTSD symptoms, and expectancies for marijuana-induced changes in those symptoms. Over 650 combat-exposed, male veterans who used marijuana at least once per week completed measures of PTSD symptoms, marijuana expectancies, and marijuana use in an Internet survey. Participants generally expected marijuana to relieve PTSD symptoms, especially those related to intrusions and arousal. Symptoms, expectancies for relief of symptoms, and marijuana consumption correlated significantly. Regressions revealed significant indirect effects of symptoms on use via expectancies, but no significant interactions of expectancies and symptoms. Combat-exposed veterans who use marijuana appear to use more as the magnitude of PTSD symptoms and their expectations of marijuana-induced relief of those symptoms increase. These results emphasize the importance of PTSD treatments in an effort to keep potential negative effects of marijuana to a minimum. They also underscore the import of expectancies in predicting marijuana use.